1. Field of the Invention
This invention relates to stamps, and more particularly to stamps for imprinting identification or other insignia into the material of work pieces, held in rotating chucks, as for example in lathes or screw machines.
2. Description of the Prior Art
Stamps of the general class here described have long been used to imprint or inscribe identification or other insignia into the material of work pieces, whether of metal or other suitable materials. One class of such device has involved the provision of a stamp having protruding characters formed on the surface thereof and means for causing the stamp to be pressed against a rotating metal work piece to cause the stamp and work piece to move together so that the characters were imprinted into the surface of the relatively softer work piece.
Typically, prior to the present invention, such stamps have been arcuate and such constructions have been subject to certain disadvantages. In the first place the shapes of such stamps renders them relatively expensive since formation of the characters on an arcuate base requires special tooling and is thus more expensive than the cost of flat platen equivalents. Secondly, it is in the nature of such stamp structures that the entire stamp and stamp holder must be removed and replaced upon wear-out or for changes in insignia. Another disadvantage in present state-of-the-art arcuate stamps is that they often require the inclusion of positioning marks preceding the desired imprint, to engage the work piece and to start rotation of the tool at the equivalent speed of the rotating work piece surface, to prevent blurring or variable depth of the inscriptions and this puts extra and unnecessary marks on the surfaces of the stamped pieces. Still another disadvantage of the state-of-the-art technique is that the speed at which parts can be marked by such arcuate stamps is limited. Particularly as applied to high speed automatic tools such as automatic screw machines, the speed limitations placed upon over-all production rates by the stamping operation limits the cost-effectiveness of such machines.